Fly-by-wire: Bad for FE?

[gone-ot]

...deceleration under load is BAD, BAD, BAD for hydrocarbon (HC) pollution, so taking the mechanical throttle "back-off" control away from the driver and giving that control to the computer is *how* most engines "meet" the EPA emissions control.

...you can 'lift' your foot off the accelerator pedal, but the computer will control the A/F ratio smoothy by adjusting air and fuel without creating the HIGH manifold vacuum condition that makes gasoline engines "back-down" like a diesel and in doing so, put raw & unburnt HC's out the tailpipe.

[99LeCouch]

The DBW throttle on my fiancee's 09 Honda Fit is much better. It responds instantly, and modulates fairly smoothly. It even lets you engine-brake a little bit with your foot off the gas.

I've used it pretty well for fuel economy purposes. My fiancee doesn't know/doesn't care it's DBW.

The Aveo is not a very good car to start. A rental Aveo has to be a form of driver torture.

[NeilBlanchard]

Hi,

Originally Posted by PaleMelanesian

How does that work?

The computer takes the data from all the sensors: temperatures, pressures, oxygen levels in the exhaust, fuel pressure, air density, RPM, etc., and adjusts the fuel input accordingly. Also, when you lift the throttle, it shuts off the fuel completely!

[gone-ot]

...*my* technical summarization:

PRO: Fly-by-Wire = decent "canned" FE and excellent emissions control

CON: Fly-by-Wire = less than "optimum" FE and interference with driver control in some hypermiling situations.

...when the computer is "in control" the driver's "options" are limited.

[Thymeclock]

Originally Posted by Old Tele man

...*my* technical summarization:

PRO: Fly-by-Wire = decent "canned" FE and excellent emissions control

CON: Fly-by-Wire = less than "optimum" FE and interference with driver control in some hypermiling situations.

...when the computer is "in control" the driver's "options" are limited.

Yes, the electronic brain (microprocessor) now controls your vehicle and it cannot be reprogrammed. Without it the vehicle cannot function. Your options are limited, at best. Electronic controls are meant to protect manufacturers from tort liability lawsuits. (Unless the electronics fail - welcome to Toyota nightmare land. <?>)

Well, the Nanny State always thinks it knows what is best for us, therefore our opinion doesn't matter. So, if you don't like it, go buy a new car, with another imbedded, unchangeable program in its electronic brain.

I just wish the government and big business wouldn't pretend that this is freedom or progress. Present day America is all about the illusion of freedom. Virtual freedom. Artificial freedom. 'Feel good' freedom. Pretend freedom. Ersatz freedom. Freedom redefined.

When something (a microprocessor) or someone else (a government or a manufacturer) is in control of you or your vehicle, you are anything but free.

When your vehicle does all your thinking for you, and you cannot override it, what you think will no longer matter. It will literally have become the vehicle between master and servant. Guess which one you will be?

[gone-ot]

...rise & rebellion of the 'Droids

[cfg83]

Old Tele man -

Originally Posted by Old Tele man

...*my* technical summarization:

PRO: Fly-by-Wire = decent "canned" FE and excellent emissions control

CON: Fly-by-Wire = less than "optimum" FE and interference with driver control in some hypermiling situations.

...when the computer is "in control" the driver's "options" are limited.

Yeah, it's a CONundrum. I feel that my favorite cars are the 1996 to 2000 era because of OBDII + (mostly?) otherwise mechanical systems.

My Dad's argument is that mechanical systems are more likely to "fail gracefully" in the sense that you have a greater *likelihood* of detecting a failing mechanical part before it fails catastrophically. However, with an electrical system, it's either working, or suddenly not working. I admit there are counter-examples on both sides, but I think this is still true overall. Maybe it would be more fair to say that the mechanical systems just have more "development time" built-in.

I would argue that we are in a transition where fly-by-wire is still maturing. I don't want it because I am old-fashioned, me likey me cables. But if it is best for emissions, it's harder for me to justify my position.

Hmmmmmm, how about an open-source fly-by-wire, OSFBW or FBWOS?

CarloSW2

[gone-ot]

...to the EPA and DOE, "...Fail Safe..." is truly a digital binary state: 1 = working, 0 = stop.

...the ECU's "limp-in-mode" was seriously diss'ed by EPA on the grounds that "if it's stopped, it's not polluting." Gee, thanks, Uncle Sam!!!

[RobertSmalls]

I had a Ford F150, ~2005, with a failed throttle pedal sensor. Ford were clever enough to give the car a high idle limp home mode, where the computer opens the throttle just wide enough to allow the truck to putter along at 30mph, but not open so far that you can't easily outbrake the engine in D. You can't do that with a cable. But then, cables don't break nearly as often as throttle pedal position sensors do.

[Allch Chcar]

That's interesting because the Current Gen Ford Focus is DBW and there is a mod on FocalJet(a Focus forum) where someone found that if the throttle body was not properly grounded the response was laggy. He ran a better ground to the battery and response improved dramatically.

Excuse me for being geeky but I'd prefer a DBW system over a cable. I race on the computer using a racing wheel and the pedals have no "feel" they're completely electronic. I find that the lack of pedal feedback works better because I can read from other sources like speed, rpm that give better inputs than pedal. While the pedal isn't topshelf it stills gives better response than any of the vehicles I've driven on the road. I don't drive cars like I race but more often than not they're family slug vans with too much carbon in the throttlebody. The pedal feedback is just feedback from the throttlebody which is coated in carbon. But if the DBW system is not properly designed it's just going to be an on/off pedal and no better response than cable throttles.

Now Brakes are better when they're powerboosted, cabled, and without ABS, there's just no better brake pedal than one that tells you if your tires are slowing down or if you're pushing it too far or you've done locked up your tires. You can't get that feeling from a electronic pedals.

DBW is exactly what Electric cars have, you can't hook a cable to the electric motor and expect it to go.